Among the most daunting tasks of tissue engineering is growing blood vessels. In order to create functional organs, a tissue engineer must intubate the growing target tissue with blood vessels. But creating the proper 3D structure to coax stem cells into differentiating into the correct kinds of endothelial and muscular cells to form the blood vessels has been a daunting task. So far most efforts using techniques like micro-contact printing and photolithography have only been able to create crude 2D structures.

But researchers at the University of California, San Diego (UCSD) -- a top player in the field of tissue engineering --have used a new method called dynamic optical projection stereolithography (DOPsL) to grow a fractal network of 3D blood vessels out of soft biocompatible gel.

In recent years stereolithography has become a big deal in the world of manufacturing of machinery and vehicles, given its ability to create 3D parts or dies. Alternatives -- such as two-photon photopolymerization -- remain far slower and less efficient, taking hours to make a part.

But for all its promise, work to adapt stereolithography to a microscopic scale is still in its rudimentary beginnings.

Funded by a $1.5M USD grant from the National Institutes of Health, the UCSD team created a working prototype of micromirrors, which direct light to solidify photosensitive liquid biogel. Controlled by the computer, the mirrors were able to pattern a network of 3D blood vessels in mere seconds.

The team -- led by NanoEngineering Professor Shaochen Chen -- says they're still a long way from simply growing blood cells to replacement organs. In the short term, however, the technology will likely first be applied to attempts to better grow and differentiate diverse tissues in the lab. For example the method could add vasculature to a growing cardiac tissue, improving its survival.

Eventually, Professor Chen, like many of his colleagues around the country, envisions a future in which mankind can simply "print" rich multi-tissue replacement organs -- say a heart, kidney, or liver -- then populate the framework with stem cells and chemicals, grow it for a couple months, then finally pop the finished product into a human.

The technology could eventually be applied to growing livers and other replacement organs.
[Image Source: Toronto Transplant Institute]

They're working hard to reach that goal, and stereolithography may play a crucial role in getting there, now that it's hit the scene.

Unfortunately ... human history tells us there are people who consider the phrase "blood is thicker than water" to be the guide for loving and caring for children. No matter what laws a country has, no matter what the social expectations are, unless a child has half of their own DNA in them they will never consider them as their own children, and even if the child does have half their DNA from that parent that doesn't guarantee acceptance.Also, it wouldn't surprise me if "tube grown" became grounds for racial segregation, inequality, and degradation of human rights in some cultures.